This invention relates to an electromechanical switch.
There are a great many different electromechanical switches on the market, designed to connect or disconnect electrical conductors. The fundamental mechanical concept of these switches is essentially the same, in that a movable, current-conducting switching element presses down on appropriate contact surfaces of the conductors or wires that connect to the switch, thus establishing the electrical connection or, respectively, the switching element is moved away from the contact surfaces, thus breaking the electrical connection. The switching element generally makes simultaneous contact with two neighboring contact surfaces, thus establishing the electrical connection between these two contact surfaces.
The switching element is traditionally moved by means of a lever which is contained in the same switch housing and is movably or rigidly connected to the switching element. This lever usually consists of an electrically nonconducting material or it is at least safely insulated from the switching element and the contact surfaces.
One inherent problem of this type of switches lies in the fact that due to the clearance needed for the movement between the lever and the switch housing it is not possible to completely seal the switch mechanism. Dirt and moisture can penetrate into the switch housing, soiling or oxidizing especially the contact surfaces and/or the switching element. This can lead to a significant deterioration of the functionality of the switch or cause it to fail altogether.
Switches which are exposed to such conditions and must therefore meet stringent weather-proofing requirements can be provided with additional seals which are traditionally positioned at least around the lever and provide a water-tight connection with the switch housing.
That is a costly solution since additional materials must be used. It also increases the size of the box, i.e. the switches thus equipped usually have greater dimensions. It is a solution that does not lend itself well to switches which must be kept small.
It is therefore the objective of this invention to introduce an electrical switch that can be produced in simple fashion and even with very small dimensions and which would permit reliable switching, i.e. circuit-connect and disconnect operations, while dependably protecting the switch unit against exposure to the effects of external moisture.
The invention meets this objective by means of an electrical switch having novel features as described herein.
A surprising discovery has revealed the possibility of sealing the switch mechanism with a diaphragm which at the same time and in advantageous fashion serves to provide electrical insulation of the free end of the switching element, which can thus function as the actuating surface of the switch and by means of which the switching element applies the contacting pressure on the contact surfaces. As an added advantage, the construction of this type of electromechanical switch is simplified insofar as separate, elastic elements serving to ensure alignment and to produce the necessary contact pressure, such as metal springs employed in conventional switches, can be dispensed with.
The elastic diaphragm exerts this contact pressure preferably by means of its defined prestressed condition between the switch housing and the switching element. This can be accomplished, for example, in that the diaphragm is pulled over the preferably pin-shaped switching element and, with a small amount of tension corresponding to the required contact pressure and skirting the contact surfaces, it is attached to the appropriate section of the switch housing.
Consequently, one single element advantageously meets the mechanical requirements (contact pressure, insulation) while also sealing the unit.
Switches of this type are especially practical for use in small electronic devices, a particular example being hearing aids.